A power supply is a device that can provide power to an electronic device, such as a server. For example, a power supply may convert power from a form that is not suitable for the electronic device (such as an alternating current (AC) power signal) into a form that is suitable for the electronic device (such as direct current (DC) power signal having a specific voltage).
Some power supplies include power factor correction (PFC) circuits that correct the power factor of the power drawn by the power supply. In particular, active PFC circuits work to ensure that the waveforms of the current drawn by the power supply and the voltage of the input AC power signal are congruent and in-phase—that is, that the phase difference between the current and voltage waveforms is as close to zero as possible and both waveforms have similar shapes (i.e., both are sinusoidal). For example, a PFC circuit may correct the power factor by using active circuitry to change the waveform of the current that is drawn to make it sinusoidal and reduce the phase difference.